convert the main index page to markdown

The main index is written in HTML. Convert it to Markdown for easier maintenance.

The styling in the HTML should be converted into a theme which is applied to all Markdown pages. See: #4

I see three ways we can go with the site.

1. All pages are in Markdown and a custom theme is used. Making a custom theme may be difficult.
2. All pages are in Markdown and the default theme or some other third party theme is used. This choice has the ugliest site. :P
3. All pages are in HTML. Updating the style and layout of the entire website means manually editing every page. Tedious.

I prefer (1) and if that is not possible then (2).

[meskarune]

I think this issue depends on #4 so I will mark it blocking